Not adding IDs

This plugin is not working very well for me. The ID’s are not being added.

I initially had it network activated, then thought maybe it would work better as a single activation (not that I could think of any reason why it would work better that way), then I thought maybe my social sharing plugin was causing problems, so I deactivated that, but none of these things seem to help make the plugin work.

Ah, I’ve found the problem. I was expecting it to work on pages, but because it uses is_single(), it only works for posts. The solution is to switch is_single() for is_singular(), or if attachments should be excluded, just add || is_page();